The present invention relates to an image forming apparatus, and particularly to a method and a device for providing variable film voltage and toning bias offset for machine diagnostic capability.
Electrophotography refers to producing photographic images by electrical means and can be used for copying documents and other graphic matter. Electrophotographic print engines are well known to those skilled in the art and are extensively used in a variety of environments, such as offices, libraries, and educational institutions.
Electrophotographic print engines are comprised of a number of subsystems, one of which is best described as the electrophotographic imagery subsystem. In this system, a light source forms an electrostatic latent image of an original document on a photosensitive medium. The photosensitive medium, as it moves within the print engine, travels adjacent to a source of tiny plastic particles called toner. The electrostatic force of the latent image on the photosensitive medium attracts the toner, thereby providing a developed image of toner particles on the surface of the photosensitive medium. The toner image is transferred through electrostatic charges to an image receptor, which is normally a sheet of paper or plastic. The image receptor then passes through a fuser which heats and melts the toner particles, thereby fixing or fusing the image of the original onto the image receptor.
As described above, several operational steps are involved in the electrophotographic imagery subsystem and include what can be described as charge, expose, tone and transfer steps. All of the steps in the electrophotographic imagery subsystem must work together properly in order to provide consistent image quality.
When the image quality of a print engine does not meet expectations due to the presence of subsystem problems, a service engineer must determine the root cause of the problem before adequately servicing the print engine. Many image uniformity issues can originate from the charging, exposure, development, transfer or cleaning subsystems. Without proper diagnostic tools, it can be difficult to diagnose the subsystem causing the loss of image quality performance.
Efforts regarding servicing such systems have led to continuing developments to improve their versatility, practicality and efficiency.
An object of the present invention is to provide an image forming apparatus comprising: a primary charger for providing a primary charging voltage on an image support; an image support for supporting an electrostatic latent image on the surface thereof; a developing unit having a developing agent support, the developing agent support retaining a developing agent, including toner and carriers, contained in the developing unit, and the developing unit converting the latent image on the image support into a toner image by causing the toner to adhere to the surface of the image support; a developing bias supplying unit for supplying a developing bias voltage to the developing agent support of the developing unit; and, a controller for controlling the developing bias supplying unit and primary charger to provide the primary charging voltage and developing bias voltage at predetermined values in order to provide diagnostic information on the image forming apparatus.
Another object is to provide a method of operating an image forming apparatus comprising the steps of: providing a primary charging voltage on an image support; supporting an electrostatic latent image on the surface of the image support; causing toner of a developing agent to adhere to the surface of the electrostatic latent image to thereby convert the latent image on the image support into a toner image; supplying a bias voltage to the developing agent; and setting the bias voltage and primary charging voltage to predetermined values in order to provide diagnostic information on the image forming apparatus.
Another object of the present invention to provide an electrophotographic print engine having a variable primary charger and toning bias offset in order to provide the necessary service and diagnostic information to troubleshoot all subsystems involved in the electrophotographic process (from photoconductor maintenance image formation to image fixation onto the output receiver). To this end, the present invention allows the electrophotographic process to be operated with parameters otherwise undesirable for the print production mode. Specifically, the present invention allows the toning of the image loop without using an exposure step. The operator can use the output created by the present invention to differentiate between exposure issues and other sources of process non-uniformities to thereby analyze the health of the various subsystems of the print engine.
The present invention provides an image forming apparatus having an image support for supporting an electrostatic latent image on a surface of the image support; a developing unit having a developing agent support, the developing agent support retaining a developing agent, including toner and carriers, contained in the developing unit, and the developing unit converting the latent image on the image support into a toner image by causing the toner to adhere to the surface of the image support; a developing bias supplying unit for supplying a developing bias voltage to the developing agent support of the developing unit; and a controller for setting the developing bias voltage, for imaging or service diagnostics.
These and other objects, features and advantages of the present invention will become more apparent in the light of the detailed description of exemplary embodiments thereof, as illustrated by the drawings.